High strength runner

ABSTRACT

A suspended ceiling grid beam is provided that has an increased beam height to provide enhanced resistance to downward deflection. The beam has a cross-section generally in the form of an inverted T, with a central web, a pair of panel support flanges extending from one edge of the web, and a reinforcing bulb extending from the other edge of the web. The reinforcing bulb has a generally planar, fin-like structure extending therefrom opposite to and generally co-planar with the central web.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 60/705,758, filed Aug. 5, 2005, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a beam or runner having a generallyinverted T cross section that is used in a support grid for suspendedceilings.

Suspended ceilings typically require a support grid comprising aplurality of interconnected beams for supporting ceiling tiles orpanels, light fixtures, air diffusers, etc. The beams, also referred toas runners or tees, are generally inverted T-shaped with a reinforcingbulb at the top, a vertical web extending downwardly from the bulb, andopposed horizontal flanges at the bottom of the web for supportingdrop-end ceiling panels. In standard practice, the height of the beam,as measured from the top of the flange to the top of the beam, isapproximately 1-½ inches, so as to accommodate the frames ofconventional fluorescent ceiling light fixtures. The beams are typicallymade in a roll-forming operation from a flat strip of sheet metal, as iswell known in the art.

It is well known that resistance to downward deflection in a beam can beincreased by increasing the height of the beam, thus increasing themoment of inertia of the beam. Modifications to suspended ceiling beamshave been proposed to increase the beam height. See, U.S. Pat. No.6,138,416, where the beam is formed with a peak or angle at the top ofthe bulb to both increase the height of the beam and to accommodate theframe of a lighting fixture that may be supported by the beam.

SUMMARY OF THE INVENTION

By way of the present invention, an improved beam configuration isprovided that has an increased beam height to provide enhancedresistance to downward deflection. The beam or grid tee has across-section generally in the form of an inverted T, with a centralweb, a pair of panel support flanges extending from one edge of the web,and a reinforcing bulb extending from the other edge of the web. Inkeeping with an aspect of the invention, the reinforcing bulb has agenerally planar, “fin-like” structure extending therefrom opposite toand generally co-planar with the central web.

The fin has narrow width in comparison with the width of the reinforcingbulb. In a first embodiment, the fin is generally planar. In a secondembodiment, the fin is more in the shape of a drop, with the narrowportion of the drop being adjacent to the reinforcing bulb.

In keeping with another aspect of the invention, the two layers formingthe web of the beam are stitched together to provide additionalresistance to torque.

Other features and advantages will become apparent upon reference to thedrawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show cross-sectional views of five different embodiments ofsuspended ceiling grid beam that include a reinforcing fin in accordancewith the present invention. reinforcing fin in accordance with thepresent invention.

FIG. 6 is a perspective view of a beam according to the presentinvention, in which the fin includes a hole for receiving the hangerwire for suspending the beam.

FIG. 7 is a fragmentary cross-sectional view of the strengthening fintaken along line 7-7 of FIG. 6.

FIG. 8 is a perspective view of a beam according to the presentinvention showing a stitching method in which the web of the beam has aseries of horizontal stitches with a vertical cut therein spaced atintervals along the length of the runner.

FIG. 9 is a cross-sectional view of a stitch taken along line 9-9 ofFIG. 8.

FIG. 10 is a cross-sectional view of the stitch prior to having thevertical cut being made therein.

DETAILED DESCRIPTION

With reference to FIGS. 1-5, a runner or tee 10 for use in a suspendedceiling is disclosed comprising a reinforcing bead or bulb 12, a centralweb 16, and a pair of opposed flanges 26 for supporting ceiling panelsor tiles, with a cap 27 covering the exposed portions of the flanges 26,all as is well known in the art.

In keeping with one aspect of the invention, the bulb 12 of the runner10 is modified to provide for a greater beam height than the standardrunner configuration. This is accomplished by forming the bulb 12 with acentral fin 14. While the bulb 12 typically has a rectangularcross-sectional shape, as seen in FIGS. 1-4, other cross-sectionalshapes are contemplated, such as the I-beam or dog-bone shape seen inFIG. 5, in which the bulb has a relatively narrow central portionbetween an enlarged top and bottom. The fin 14 extends from the bulb 12generally opposite to, and coplanar with, the web 16 of the runner. Thisprovides for greater strength, and thus greater resistance todeflection, than a runner of identical configuration but without thefin. The fin 14 preferably has a generally flat configuration (as seenin FIGS. 1-3), and is narrow in width as compared to the width of thestrengthening bulb 12. However, other narrow configurations may be usedfor the fin 14, such as the inverted drop shape seen in FIGS. 4 and 5.The fin 14 may be of different heights, with the overall height of therunner or tee being maintained, as shown in FIGS. 1 and 2. Thus, whilethe total height of the tee is a predetermined value, the heights ofeach of the bulb 12 and fin 14 may vary.

The enhanced strength provided by the fin configuration permits therunner to be formed of thinner material than the prior art runnerwithout compromising the beam strength of the runner. This results in arunner that is more economical to manufacture (because less material isrequired) is easier to handle, particularly in bulk or carton quantities(because each runner is lighter in weight), and is easier to cut.

The fin 14 also facilitates the creation of a runner suitable for longspans by stacking a second, inverted, runner on top of the first runner,with their fins 14 lying along each other, and preferably secured toeach other through the fins. Such a configuration can also be used tocreate a coffer.

With reference to FIG. 3, the fin 14 can be reinforced by introducing anelongated strengthening element 18 of the same material of the remainderof the runner that is bonded in place between the opposed faces of thetwo layers that comprise the fin by, e.g., adhesive, solder, spotwelding, plasma welding, toggle locks, or by stitching or the creationof embossed hanger wire holes in the fin, as discussed below.

To provide the beam with added resistance to torque, the two layers ofthe web are preferably secured to each other by means of lockingstitches or lances that mechanically join together the two layers of theweb. See, e.g., U.S. Pat. No. 4,489,529, which is incorporated herein byreference. This patent shows the web of a suspended ceiling beamfastened together by either a horizontal or a vertical stitch.

The stitch 20 may be of any configuration known in the art, but ispreferably of the configuration shown in FIGS. 8 and 9. FIGS. 8 and 9show a 2-axis stitch 20 applied at spaced intervals along the length ofthe web. This stitch 20 includes a vertical cut 21 to resist motion inthe horizontal direction.

The stitches 20 are preferably made as part of the roll formingoperation for the beam in which the beam is passed between a pair ofcooperating rollers. One roller has a series of small punches withopposed cutting edges spaced around its circumference, while the otherroller has a continuous circumferential groove aligned so that thepunches penetrate the groove. Thus, in a first roll pass, the web passesthrough the rollers, and the punches in the first wheel cut out parallelslots and displace a slug out of the plane of the web and into thegroove of the second roller, with the slug from one of the layersprotruding through the hole in the other layer to form ahorizontally-oriented D-shaped stitch, when viewed in horizontal sectionas shown in FIG. 10. This resists vertical displacement between the twolayers of the vertical web. See also U.S. Pat. No. 6,047,511, FIGS. 1-2a and associated description, and U.S. Pat. No. 5,979,055, FIGS. 1-3 andassociated description, both of which are incorporated by reference.

The beam is then passed through a second pair of rollers in which one ofthe rollers has an edge that creates a vertical displacement in theD-stitch formed in the first roll pass to complete the stitch. As shownin FIG. 9, the illustrated stitch includes a vertical cut thatcompletely severs the layers of the web. However, this is not requiredand the second roll pass operation may simply press a central portion ofthe D-shaped stitch back into the plane of the layers forming the web.

As shown in FIG. 7, the fin 14 is preferably provided with a series ofspaced holes 22 for receiving the hanger wire 24 for suspending theassembled grid from the ceiling. Preferably, the series of holes 22 isspaced so that a hole 22 is aligned with apertures in the web of thebeam for receiving the cross beams. Having the fin 14, rather than theweb 16, carry the hanger wire allows for the hanger wire to be alignedwith the cross-tee and for the hanger wire to be more tightly wrappedabout itself. This, in turn, lessens the likelihood of damaging theedges of the ceiling tiles by the hanger wire when the tiles are droppedinto place on the flanges 26 of the runner 10 because there is greaterclearance. The greater clearance also facilitates faster installation ofthe ceiling tile. The hanger holes 22 are also preferably formed as partof an embossment 28 for additional strength. The embossment 28 alsoprovides a tapered hole, which allows easier hanger wire insertion.

Thus, an improved beam for a suspended ceiling grid has been provided.While the invention has been described in terms of certain preferredembodiments, there is no intent to limit the invention to the same.Instead, the invention is defined by the scope of the following claims.

1. A grid tee for a suspended ceiling having a cross-section generallyin the form of an inverted T with a central web with first and secondopposed edges, a pair of panel support flanges extending from the firstedge of the web, a reinforcing bulb extending from the second edge ofthe web, and a fin that is generally co-planar with the central webextending from the reinforcing bulb opposite to the central web.
 2. Thegrid tee of claim 1 wherein the fin and the reinforcing bulb each havinga height that is variable, with the sum of the heights of the fin andthe bulb being a predetermined value.
 3. The grid tee of claim 1 whereinthe fin comprises a double layer web with a reinforcing strip disposedbetween the layers.
 4. The grid-tee of claim 1 wherein the fin includesa series of spaced apertures adapted to receive hangar wire forsuspending the grid tee.
 5. The grid tee of claim 1 wherein the finincludes a series of spaced embossments, each embossment having anaperture adapted to receive a hangar wire for suspending the grid tee.6. The grid tee of claim 1 wherein the fin has an inverted, drop-shapedcross section.
 7. The grid tee of claim 1 wherein the web comprises adouble layer, the layers being secured together by a plurality ofstitches at spaced intervals along the web, the stitches being formedwith a pair of opposed horizontally oriented cuts through the two layersof the web and each stitch including a vertical displacement to resistmotion in a horizontal direction.
 8. The grid tee of claim 7 wherein thevertical displacement in each stitch comprises a vertical cut throughthe stitch.
 9. The grid tee of claim 7 wherein the vertical displacementin each stitch comprises a central portion of each stitch beingdisplaced back into a plane defined by the layers of the web.
 10. A gridtee for a suspended ceiling, having a cross-section generally in theform of an inverted T with a central double layer web having first andsecond opposed edges, a pair of panel support flanges extending from afirst edge of the web, a reinforcing bulb extending from the second edgeof the web, and a plurality of stitches at spaced intervals in the webto secure the layers together, the stitches being formed with a pair ofopposed, horizontally oriented cuts through the two layers of the weband each stitch including a vertical displacement to resist motion in ahorizontal direction.
 11. The grid tee of claim 10 wherein the verticaldisplacement in each stitch comprises a vertical cut through the stitch.12. The grid tee of claim 10 wherein the vertical displacement in eachstitch comprises a central portion of each stitch being displaced backinto a plane defined by the layers of the web.
 13. A grid tee for asuspended ceiling having a cross-section generally in the form of aninverted T with a central web with first and second opposed edges, apair of support flanges extending from the first edge of the web, and areinforcing bulb extending from the second edge of the web, thereinforcing bulb having a cross section with a narrow central portionand a relatively wider top and bottom portion.